They say you should never meet your hero. He'll always let you down. Well, I have, and he didn't.

The 1988 Olympic Games in Seoul was memorable for two things - Ben Johnson's red-eyed corruption of the 100-metre sprint, and double Olympic gold medallist diving champion Greg Louganis hitting his head on the board.

"My first feeling was one of embarrassment" - says Greg Louganis of his 1988 encounter with the board

Louganis was the golden boy of the diving pool, with two golds to his name from the previous Games in LA. He was expected to become the first man in history to defend both his springboard and platform titles.

So how did it feel when it all went so wrong during the springboard preliminaries, and he went splat in front of all those people?

"My first feeling was one of intense embarrassment," he remembers, 24 years later. Then that trickled into anxiety. But I have to admit, there was also a feeling of relief, because I was under so much pressure to do well, and suddenly everyone stopped expecting anything. It freed me up."

No, I'm not sure how they do it, either

There was more riding on Louganis' success at the 1988 Games than his many worldwide fans could possibly imagine.

The prize athlete had been diagnosed with HIV status six months before, and was waking himself up with an alarm every four hours throughout the Olympic event, to take medication that could have brought down a horse.

At that time, Louganis wouldn't even have been allowed to travel to South Korea if his condition had been public knowledge. As it was, he explains to me how his expensive medications were being smuggled into the US under a false name to keep secret that one of the country's most celebrated sportsmen was afflicted with a condition unequalled in the stigma attached to it.

To cap it all, he was being abused in his relationship, with a partner who was threatening to expose his HIV status if Louganis dared leave him. All in all, it was a rough ride leading up to Seoul.

Somehow, the diver of Swedish/Samoan descent who grew up in California with his adopted parents had the strength - both physical and mental - to carry this on his shoulders, get back on the board, grin to the spectators, make a gesture of prayer, and execute a dive that would win him his gold medal.

Only Greg Louganis and his coach knew how hard-earned his gold medals at Seoul actually were

He went on to win his fourth gold on the 10-metre platform too, a feat that remains unique for a male diver in the history of the Games.

How on earth, I ask him, did he summon the resources to climb up the steps again and throw himself into the air, with all that going on?

"I remembered my mum," he explained. "She always thought the best of me, whatever I did. You're meant to make as little splash as possible when you enter the water, but even if I belly-flopped, I knew she'd be watching the TV, clapping her hands, and saying 'great stuff, you made such a nice splash.'"

It was only with the two medals around his neck that Louganis finally allowed himself to break down.

"That evening, my coach and I just cried together. We said to each other 'nobody knows what we've achieved'."

The scale of his achievement, but also fresh scandal, emerged in the mid-1990s when Louganis revealed he was gay and HIV positive, by writing a best-selling autobiography, making a record-breaking appearance with Oprah, and competing in the Gay Games.

Greg Louganis, looking as fit at 52 as only an Olympian is allowed

People remembered only his blood in the pool in Seoul, his corporate sponsors mostly dropped him, and Louganis had to clarify that he had never been in danger of infecting anybody.

"The only person I told in Seoul was the doctor stitching my head," he remembers. "I had to protect him, and he was an honourable man who, as far as I know, never whispered a word."

I'm speaking to Louganis today near his home in Malibu. We're having lunch in the healthiest-looking eatery imaginable overlooking the ocean, and tanned, daily-yoga-tuned Louganis fits right in. He looks about 15 years younger than his 52 years, and describes himself as "fitter than I have ever been". With daily medications of advanced medications and a healthy lifestyle, the virus is hardly present in his body.

Attitudes, too, have thankfully long since changed, and he is rightfully regarded as one of the great American sporting heroes, with the role of mentor to the US Olympic team currently competing in London.

"I've had people come up to me crying saying I've touched their life in some way.

"One man came up to me at a book-signing, saying he had been on the verge of killing himself, but had read my story and decided not to, and it was incredibly moving. It's a privilege to be able to do that for someone, it's not something I'm casual about, but I can't carry it too heavily, otherwise I'd never get anything done."

Does he think closeted gay celebrities owe it to their fans to come out and set an example? Louganis gives an answer surprising in its understanding and compassion, and makes a point I've not considered before... "It would be great if they did, but if they are forced to come out before they're ready... where's the honour, dignity and good example in that? It doesn't help anybody."

Of all Olympic sports, it is diving, along with gymnastics possibly, that has always seemed to me to incite the same 'ooh' and 'aah' reactions of the magic circus tent. It requires the same combination of expertise and personal discipline known to all Games participants, but also a willingness to contort, defy gravity and give way to the unknown.

They say you should never meet your heroes... but very occasionally they don't let you down

So, as we Brits get ready to pray for Tom Daley once more as he steps up for Olympic glory, can Greg please explain how these unusual people can fling themselves into the air and exercise such grace in motion? It just seems so... unnatural.

Patiently, he tries. "Well, you've done it thousands of times in training, so by the time it comes to competition and all those eyeballs on you, it's really not so bad. I guess you have to concentrate on your moves, it becomes a practical challenge really. As well as a dance. And then... surrender." And his eyes light up at the memory.

Finally, I put it to him that, back in Seoul in 1988, if he'd hit the board, had his head stitched up, gone on to defend his two golds AND come out with his HIV status, he might have been the only athlete in the world to displace Ben Johnson on the front of every newspaper in the land.

Greg's eyes open wide in surprise. "Do you know, I never, ever thought of that?"

He chuckles. "Not once in twenty years..."

Brit Tom Daley in action, one of many hoping to emulate the success of Greg Louganis...